Radio receiving system



M1103 n93. 5 B, BRADBURY,

RADIO RECEIVING SYSTEM. FILED SEPT- 15. I920.

Patented-dun v BUR/IKE BRAlDBURYyOJE SCI-IIENECTADY, NEW roan, ASSIGNUR T GENERAL ELEETRIU UDMIPANY, A. CORPQBATIUN U35 NEW YORK.

RADIO RECEIVING SYSTEM.

Application filed tcptemberlti, race. Serial Ito. 410,529.

To all whom it may concern:

Be it known that i, BURKE BRADBURY, a citizen of ,the United States, residing at Schenectadyfiin the county of Schenectady,

State of New York, have invented certain new and useful Improvements in Radio Bieceiving Systems, of which the following is a specification. fhe present'invention relates to radio re- 0 ceiving systems, particularly to systems for receiving continuous wave signals.

In some cases where it is desired to receive continuous wave signals by some method, such for example as the heterod he method, for rendering such signals audi le, it will be found difiicult to tune a receiving system sharply enough to eliminate the effects in the receiver of stations of neighboring wavelength which are either of higher 0.power or located much nearer a receiving station than the one from which signals are to be received.

llhe object of my invention is to overcome such difficulties as the one mentioned and to provide a means for eliminating the efiect in the receiver of interfering signals. The novel features, which I believe to be characteristicof my invention are set forth with. particularity in the appendedclaims.

The invention itselffhowever, both as'to its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawing in which I have illustrated diagrammatically one way in which my invention, may e carried into efi'ect. r

I have indicated in the drawing an an terma 1 with the usual tuning inductance 2 ,and a coupling transformer 3 by means of f; which the received signals are impressed upon the grid circuit of a detector 40f the electron discharge type; The plate and grid circuits of the detector are coupled together at 5 in order that the detector may generate local oscillations of a frequency slightl different from that of the signals whic are to be received. Coupled to the plate circuit of the detector 4: by means of the trans to formert is a separate circuit in which are. provided two frequency traps. One of these which comprisesthe capacity 7 and parallel inductance 8 is tuned for the frequency of the "signals to be received the usual telephone receiver-f9, or any other desired form of indicator, being connected in parallel'to this trap. The second trap made up of the condenser 10 and parallel. inductance 11 is tuned to the frequency of the interfering signals which it is desired to suppre ss. This second trap offers a high impedance in the circuit to the flow of currents of the interfering frequency and thereby prevents such currents from affecting the telephone receivers 9. In case the second frequency trap i does not completely prevent the interferingslgnals from affecting the telephone receivers a coupling 12 may be provided between the two frequency traps for the purpose of impressing upon the first frequency trap a current of the proper phase and intensity to neutralize any current of the undesired frequency which may flow in the first trap.

l have found that it is possible by the system indicated to eliminate the effect upon the receivers of signals produced from nearby stations of high power and of wave length differing only slightly from that of signals which are to be received from a distantstation. i

While I have indicated and described only a single way of carryingmy invention into effect, it will be obvious to those skilled in the art that many modifications in the type apparatus employed as well as in the circuit connections used may be made without departing from the scope of my inven tion as set forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is

v 1. The combination in a signal receiving system of a detector, a circuit upon which currents of audio frequency produced by said detector may be impressed, a frequency trap in said circuit which is resonant to the frequency of the signals to be received, and a second frequency trap in said circuit which is resonant to the frequency of interfering signals which it is desired to suppress.

2. The combination in a signal receiving system of a detector, a circuit upon which currents of audio frequency produced by said detector may be impressed, a frequency trap. in said circuit which is resonant to the MM frequency of the signals to be received and a second frequency trap in said circuit which. is resonant to the frequency of interfering signalscwhich it is desired to suppress, and. a coupling between said-freq no -;:urrents 0f a dash smd dewctor and I ma,

3. In :1 53 3mm for race T coni'iimous waive signals i11 continumls wave Si ducing curl-mats of audio 1117.6 m ved mm the received'signals, a cirruit u i Mi mm (14 the eun ents of audio i QEQHBH- :mdio 'mu uen pressaci, an indicator 0 2? f ref: :0 said Circuit in such 21 mm as aifected by gurmqis of a impressed upon said cimu reetiy assnciated with S91v5 impresset i upon said cii'vni said indiczzfi.

n a sys'tenl 1 con nuo'us mg c-ant'muour' detector for 

